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package http
import (
"errors"
"net/http"
"strconv"
"time"
zipkin "github.com/openzipkin/zipkin-go"
"github.com/openzipkin/zipkin-go/model"
)
// ErrValidTracerRequired error
var ErrValidTracerRequired = errors.New("valid tracer required")
// Client holds a Zipkin instrumented HTTP Client.
type Client struct {
*http.Client
tracer *zipkin.Tracer
httpTrace bool
defaultTags map[string]string
transportOptions []TransportOption
}
// ClientOption allows optional configuration of Client.
type ClientOption func(*Client)
// WithClient allows one to add a custom configured http.Client to use.
func WithClient(client *http.Client) ClientOption {
return func(c *Client) {
if client == nil {
client = &http.Client{}
}
c.Client = client
}
}
// ClientTrace allows one to enable Go's net/http/httptrace.
func ClientTrace(enabled bool) ClientOption {
return func(c *Client) {
c.httpTrace = enabled
}
}
// ClientTags adds default Tags to inject into client application spans.
func ClientTags(tags map[string]string) ClientOption {
return func(c *Client) {
c.defaultTags = tags
}
}
// TransportOptions passes optional Transport configuration to the internal
// transport used by Client.
func TransportOptions(options ...TransportOption) ClientOption {
return func(c *Client) {
c.transportOptions = options
}
}
// NewClient returns an HTTP Client adding Zipkin instrumentation around an
// embedded standard Go http.Client.
func NewClient(tracer *zipkin.Tracer, options ...ClientOption) (*Client, error) {
if tracer == nil {
return nil, ErrValidTracerRequired
}
c := &Client{tracer: tracer, Client: &http.Client{}}
for _, option := range options {
option(c)
}
c.transportOptions = append(
c.transportOptions,
// the following Client settings override provided transport settings.
RoundTripper(c.Client.Transport),
TransportTrace(c.httpTrace),
)
transport, err := NewTransport(tracer, c.transportOptions...)
if err != nil {
return nil, err
}
c.Client.Transport = transport
return c, nil
}
// DoWithAppSpan wraps http.Client's Do with tracing using an application span.
func (c *Client) DoWithAppSpan(req *http.Request, name string) (res *http.Response, err error) {
var parentContext model.SpanContext
if span := zipkin.SpanFromContext(req.Context()); span != nil {
parentContext = span.Context()
}
appSpan := c.tracer.StartSpan(name, zipkin.Parent(parentContext))
zipkin.TagHTTPMethod.Set(appSpan, req.Method)
zipkin.TagHTTPPath.Set(appSpan, req.URL.Path)
res, err = c.Client.Do(
req.WithContext(zipkin.NewContext(req.Context(), appSpan)),
)
if err != nil {
zipkin.TagError.Set(appSpan, err.Error())
appSpan.Finish()
return
}
if c.httpTrace {
appSpan.Annotate(time.Now(), "wr")
}
if res.ContentLength > 0 {
zipkin.TagHTTPResponseSize.Set(appSpan, strconv.FormatInt(res.ContentLength, 10))
}
if res.StatusCode < 200 || res.StatusCode > 299 {
statusCode := strconv.FormatInt(int64(res.StatusCode), 10)
zipkin.TagHTTPStatusCode.Set(appSpan, statusCode)
if res.StatusCode > 399 {
zipkin.TagError.Set(appSpan, statusCode)
}
}
res.Body = &spanCloser{
ReadCloser: res.Body,
sp: appSpan,
traceEnabled: c.httpTrace,
}
return
}
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